Masking tapes are used in painting, lacquering and the like, to protect an area from being treated, i.e. to establish a clear line of demarcation between two areas. For example, in repainting a portion of an automobile, a masking tape would be used to protect an area not to be repainted.
Masking tapes have a backing and an adhesive face. The adhesive face is of limited adhesion so that the tape can readily be removed from the surface to be protected after the operation is complete. The backing is generally paper, usually slightly creped to provide some stretch as might be needed in establishing a curved line of protection.
The backing is usually hand-tearable since the tape is sold in rolls and the user finds it easier simply to tear the tape off the roll cross-wise to the needed length.
For the desired tearability and/or adhesion it has been found necessary first to saturate the paper backing, e.g. with a styrene-butadiene copolymer, then to dry and apply the adhesive layer. The saturation serves to protect against mildew and possible water damage, to prevent paints from penetrating through the porous paper and prevents tape delamination.
The tape is made in wide width and rolled up, being cut into narrow widths, as desired, either before or after rolling up, possibly with additional steps of re-rolling.